Fuel control for gas turbine engines



March 4, 1958 w. J. HALL ET AL 2,325,397

FUEL CONTROL FOR GAS TURBINE ENGINES' Filed March 29. 1949 2 Sheets-Sheet l INVENTOR. WALO J.

Mal'h 4, 1958 1 w. J. HALL ETAL 2,825,397

FUEL CONTROL FOR GAS TURBINE ENGINES Filed March 29, 1949 2 Sheets-Sheet 2 FEZ' l A.

INVENTOR.

ATMP/vf( 2,825,391 Patented Mar- 4, 19585 FUEL CoN'rRoL non GAS TURBINE ENGINES Waldo J. Hall and Robert A. Parsons, South Bend, Ind., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application March 29, 1949, Serial No. 84,056

10 Claims. (Cl. 15S-36.3)

This invention relates to a fuel control system for gas turbine engines, and particularly for turbojet and turboprop engines of the type commonly used in aircraft. The ultimate aim in a control for such engines is to enable a pilot or operator to accelerate and decelerate to selected speeds or loads at will with maximum engine efficiency and without producing dangerously high temperatures in the burner system upon acceleration or burner failure or die-out upon deceleration. Ordinarily, the mass ow of air to the burners is a substantially linear function of engine speed and the rate of fuel feed may, therefore, be a function of or proportional to engine speed subject to correction for changes in entering air density. A fuel feed and power control device which effectively operates to maintain the rate of fuel feed within predetermined temperature limits as a function of engine speed is disclosed in the copending applications of Frank C. Mock, Serial No. 596,620, now Patent Number 2,581,276, granted January l, i952, and Serial No. 716,154, now Patent Number 2,689,606, granted September 2l, 1954, and assigned to the assignee of the present application. With such a system, the control may be set to operate within any predetermined temperature limit upon acceleration irrespective of how suddenly the pilot increases his power lever setting. Again, upon deceleration, the control lever may be moved back to the idle stop with a minimum likelihood of burner failure.

In engines having certain characteristics, however, there is a tendency to surge and even stall at certain speeds unless a predetermined ratio of fuel-to-air is maintained, and such ratio may not always conform to an upper temperature limit throughout the acceleration range. Also, neglecting surge, an engine may have an efciency characf teristic such that to maintain a constant temperature within a certain or given limit during acceleration, it will be necessary to feed fuel at a substantially linear rate with respect to engine speed until a certain speed is attained, and then increase fuel feed above the linear rate. This results from the fact that the air ow characteristic of certain engines, notably those utilizing axial ow com# pressors, departs more from a linear function of engine speed as the speed increases than do other types of engines. Again, upon deceleration, to insure against burner failure in certain engines, it may prove of advantage to momentarily hold the fuel-toair ratio at a higher value when the pilot initially throttles back than would be the case in other engines. A device which will automatically meter fuel along different temperature limits over both the acceleration range and deceleration range is disclosed in the copending application of Howard J. Williams, Serial No. 408,233 (led February 4, 1954), which application is a continuation-in-whole of the now abandoned application Serial No. 42,302, filed August 3, 1948 (common assignee); it operates as a function of engine speed and is primarily adapted for use with the control of the above noted Mock applications. The device illustrated in the Williams application may not prove adaptable to engines having certain characteristics, and the primary object of the present invention is to provide a fuel control of this type which may be considered an improvement on or as an alternate form with respect to that disclosed in the said Williams application. More specifically, the invention has for its main object to provide improved means in a fuel feed system for a gas turbine engine whereby the rate of fuel feed to the burners is varied automatically along a single acceleration curve and a single deceleration curve at any given ambient air density, to obtain maximum eiciency in the high power range of operation and to avoid burner failure or die-out upon throttling back to the idle or low power range of operation.

The foregoing and other objects and advantages will become apparent in view of the following description taken in conjunction with the drawings, wherein:

Figure l is a vieW` in sectional elevation of a fuel control device for a gas turbine engine in accordance with the invention;

Figure 2 is a sectional schematic view of the device of Figure l with the fuel enrichment control valve unit removed and shown enlarged at the top of the figure to facilitate reading of the drawing; and

Figure 3 is a curve chart illustrating the operation of the control.

In Figure l, one of the combustion chambers and associated burner of a gas turbine engine is generally indicated at 10; it is supplied with air by means of a compressor, not shown, and with fuel from a control de-v vice to be described by way of a fuel manifold 11, pipe or conduit 12 and burner nozzle or atomizer 13. The fuel is ignited upon discharge and the expanded air and products of combustion are discharged through a turbine (also not shown) which drives the compressor, the remaining unexpended energy being used either for iet thrust or for driving a propeller or for both, depending upon the particular type of engine involved.

The fuel control proper comprises a regulator section or body 14 (compare Figures 1 and 2) which is divided into a pair of chambers 15 and 16 by a metering head diaphragm 17. A regulator valve 18, provided with a series of ports 18', is connected to the diaphragm 17; it is hollow and is slidingly mounted in a casing 19. Fuel is delivered to the regulator from a suitable source, not shown, by way of conduit 20, 20 and chamber 21. A positive displacement pump 22 maintains the fuel pressure in chamber 21 (supply or P1 pressure) at a predetermined value as determined by the setting of a bypass valve 23. When this valve opens, fuel is returned to the low pressure side of the pump 22 by way of a conduit 24. The valve 23 is preferably vented to metered fuel (P4) pressure by way of passageway 25 and charnber 26, a spring 27 being mounted in the latter chamber and normally urging the valve toward closed position. Thus, the supply pressure in chamber 21 is always maintained at a predetermined value above metered fuel pressure as determined by the force of spring 27.

Al control section or body is generally indicated at 30; it contains a throttle or governor valve 31, which is slidably mounted in a valve body 32 having a hollow tubular extension 33, the valve being provided with one or more metering or feed restrictions 34 adapted to register with coasting restrictions 34 in the valve body. Fuel at Pg'pressure in chamber 15 ows into the tubularextension 33 and thence through metering restrictions 34, 34 to annular metered fuel chamber 35. From the latter chamber, the metered fuel flows across a cut-olf valve,

generally indicated at 36, and then by way of conduit 37 to the fuel manifold 11 of Figure l.

The throttle valve 31 is of the all-speedgovernor type; it is provided with a governor spring 4t? which may be selectively set or tensioned'by the pilot through suitable linkage including lever 41, shaft 42, adjustable rod or of this dilierentialor to engine spee'drdir'ectly.

"compressor, Y

lhrks43arnfi44fshaft y45 and lever vWhen lever 1 A is turned clockwise, the springY 4l) is tensioned and 'valve 31 is simultaneouslyV moved in a direction to increase the area ofthe feed or metering restrictions 34, 34'; also, the

right-hand' end Vof the stem-of valve 31`acts vtoreset'a l' pair'of 'g'ov'e'rnor lweirghts 47 (only one of whichis visible Y Yin Figure 2`) 'mounted to rotate with an enginedriven goverhorshaftAS provided with a drive spline 49 adapted to have'a suitable drive connection with the engine. When thefselectedspeed is reached, theY governor lweights balance 'lhe fuel pressure diierential across the regulator diayphragm 17, ata ygiven governor setting and eonstantj` density, is equal to and balances'the .force setV up Yby the centrifugal head generating weights. 50; it is substantially proportional to the square of engine speed and willvaryV Y if at a given engine speed'the throttle with engine speed. or governor valve 31 is'repositioned, the regulator valve 18 Ywillealso be repositioned due to the fact that the reguthe' governorlspring and an equilibrium condition is at- Y tained, whereupon'the engine Vwill Yoperate at a substantiallyV constant' speed YforV the particular setting of the pilotfsy control lever. Y t Y "The regulator lvalve 1I8"i`sV positioned automatically as a across the VVthrottle valve Q31 Within predetermined upper and iowerrtempeiaturelanddie-out limits irrespective; of

, Vhow 'suddenly the :pilot may increase-'or Vdecrease lthe area.

' ofthe metering restrictions 34,`34.f In the exampleV illus- Y trated, this .isaccomplished by applying thethrust exerted Y lby a pair of centrifugal weights 50{(only one lof which Vis visible `in`;Figu1e v2) to :the regulator 'lvalve 18 and its fY function of engine speed and will maintain the `fuel head latordiierential will be out of balance with the dierential i;

across -the throttle valve. vAs the governor valve ,31- opens or closes to maintain thetspeed selected by "theisetting ofl the governor, the regulator Vvalve .18 opens orl closes to maintain the fuel ,head'or pressure differential across the valver 31 in accordance with the particular speed atwhich the engine is operating.

The density control ci'rcuitor passageway c onsistingrof the control jets 62, chamber 16, passage 63, fvalve.;cham ber 64Vand passage 65 is in parallel with the main flow passage across the throttle Yor governor valve 31 VbyzwayY coactingfdiaphragm i7.A These-weights 50 are preferably Y mounted to rotate with the `engine driven shaft 48V along with the all-speed governor weights v47. The weights 50, however, ',act independently of thel weights 47." Thus,

Y while the weights 47 act on the inner end o f the st emof t fora giyen position ofy needle 560 (constant density) the Y the throttle or governon yalve 31,V the weights S0 act onY Y e afsliding sleeve having'a'ldriving connection with =the shaft 48; said'leeve in'turn 'having' anoperating con-VV nection withtheupper end of a lever 52, the latter being fulcrumed atf53 and atits Vlower .endjbeing Yforked and contacting a thrust `bearing 54Smounted'on the st'e'mof the regulatonvalve 13." the .speed of VtheY engine driven Y shaft 48 `increases', the weights'!) move radially outward 'Y and exert a forceon the'regulato'r valve Y18 lin a direction Y by 'fuelpressure acting onythe Ydiaplzu'agin17in a direct1on tend1ng.to:`close'sa id valve, `the resultant differential belng,substantially?proportional' to the squareV of engine speedi, Thisedifferential is prportional'to that imposed` Vacross the -throttle'valve '31, andfor any Ygivenposition of the latter valyeV (assuming constant density) Vthe velocity y and hence'ttlieirate of'fuel fllowl across the metering Vre.r

strictions 34, 34 willbe proportional tothe square vroot VA'n adjustable stop'55determines the maximum open positxonof the regulator valve 1,8, lwhile a springi56acting on the diaphragm 17determines the minimum meteringV head at engine speeds which'maybe so low asfto produce instability in the regulator system. t Y Y #Since the'supply of airY totheY engine burners Willnot onlyvary-.w1th engine speed, ibut 'also with changes in 'Y' density due to changes in pressure andrtemperature' and aircraft jspeed (ramV pressure), a density compensating Yc1rcu1t .1sprovided. This consists of a contoured vneedle 60 whichcont-ro'lsfian oriiice 61 in series with one or more fixed. control 4jets 62, -communicating chamber 15 with chamber 16v across Vthesregulatorf diaphragmY 17. FromY .Y chamber 16, fuelmay'tiowitothe metered fuel (P4 pres-V Y sure) chamber by wayof passage163, Vvalve chamber 6.4, oriicer61land passage '65'.` TheV density needle 60 is `mounted to slidein a sealed hearing 66'arr`d atitfsflower end has an operating connection with an Varm or lever 67 securedon the adjacent end of a shaft :68,"th`ey opposite end ot said shaftrhaving an' operating connection Awith a density responsive spring .loaded V.capsul'ef69 by means of an arm-or lever 70 and rod`71. V.The bellows orcapsule 69 1s mounted 'm Va housing 72yen`te'd at 73:the unit as a Whole being located where itwill V`be exposed to changes in pressure and temperature. .ofthe .air

The fuelregulatcr .and its interrelated density compensating circuit operates as follows: i Y

liowing to 'the of` chambers V15, 15 and metering restrictions:34,A 34";

' All flow throughf'the densitycircuit must'passV through l thecontrol jets 62andvariable orifice 61 Ycontrolled by 'needle 60;V kSince at a given engine speed Vthe diierentlalY across the regula-tordiaphragm remains;constantythe.1V

flow through the fixed-jets. 62Y will also remain constant, and the drop' across the Yvariable orifice 61 `at constant flow will vary Yinversely as the square Vof Y,its area, and

drop across orifice 61'will be proportional to theY drop across the `jets l62.1-The sumgof the drop'across `the i orice 61 andthe drop across the jets 62 is equal tothe drop across the governor or throttle valve 31, andfat any: Y

fixed position of needle 60, the total drop will be rsub tending toopenithe latter; this Vfoi-'ce'is opposed, however,

increases the P12-#P3 differential across the regulator Vdia- Y phragm 17 at l the 'then existing `speed and ithrows the diierential out .of balance iwith the centrifugal Yhead generatinglweights 50 whereupon the regulator valve 18 moves toward closed position, andthe iate 'offuel feed and hence engine speed is" reduced Vto a point where-the differential isagain inV balance withgthe saidV weights; Should there heran increase lin entering lair density, the foregoing sequence' .of ioperationswillbe reversed;4 alt',

will Vthus'beseeu that the density circuit senses the pres- Sure Ydifferential across the governor Avalve'in order Yto correct theposition of Ythe regulator v'a'lveforV .variations in compressorfinlet air pressure and temperature. Also; at'anygivenengine spee'dfas determinedbythe'setting of` its.

the: governor,.,the position of the valve 31 will remain substantially constant irrespective Lof .changes inientering air dcnsitm'lbut 4fuel ow will still vary in relation to such` changes ldue tos-variation inthe fuel metering head.

..For a` :more .complete illustration .and descriptionaof.

the device vso fai described and shown :schematically in Figureyreferencemiay he had .to Vthe copending 4applica-Y t tions fof 'Frank Mock above noted, andparticularly Vto Patent Number 2,689,606, .which illustrates themechaua Y' ical parts more'in'detailA y Y i, Y

The means whereby .the rateiof fuel ffeefd tothe burnersY isva'ried along Ava 'single acceleration curve and la sing-leV deceleration curve totobtainpirnproved -eiliciency andV avoid burner. failure is streelt/'nat the top of Figure 2j in enlarged section andA removed from the remaining parts Vofthe controleY It `comprisesavalve whiohisV shown asY-of thejbal-l type fbut'could be acontoured `needle or Y analogous valve element, the said valvev controlling'anN orice'76fglocated ina `passageway defined V"Dyia' conduit' Y 77, Vorifice 76, valve chamber 76', outlet orifices 83,.V annular ,chamber84, and Vconduit 78, the latter terrrlinat` ing in the valve chamber64 of the density compensating circuit heretofore described. The conduit 77 has its pick-up or entrance end located in the governor chamber 79 of the fuel control body 30 for a purpose to be described. The seating pressure of the valve 75 may be adjusted by means of a threaded plug 80 which at its inner end provides a retainer or seat for a spring S1. The plug is located in a valve body 82 formed with the outlet orifices 83 and an annular external recess defining the chamber 34. A calibrated restriction 85 is preferably located in the conduit 77 upstream of the valve 75 when using a valve of the ball checl: type, to obtain the desired metering characteristics. Such characteristic could, however, be obtained otherwise, as by using a contoured needle instead of the ball, by contouring the valve seat, by coordinating the valve spring rate with the ball check, or by other suitable metering devices.

vIt will be noted that the governor chamber 79 is partly closed off from the main chamber 15. -In this chamber 79 are the rotating all-speed governor weights 47 and the centrifugal head generating weights 50, which generate a pressure P2' in chamber 79 varying as a function of engine speed. The weights 47 and 50 augment or amplify the pressure in chamber 79 in a manner which is similar to the generation of pressure by a centrifugal impeller, thereby amplifying the head P2'-P3 across valve 75 as the engine accelerates. At a predetermined engine speed the augmented pressure head P2-P3 is sufficient to overcome spring 81 and open valve 75, thereby allowing an additional supply of pressurized fuel to iiow from passage 77 to passage 7S and P3 pressure chamber 16. The resulting enriching action of regulator valve 1S is described in the following statement of operation.

Operation Usually an electric starting motor is used to crank a gas turbine engine while at the same time fuel is fed to the burners and ignited, cranking being continued until the engine attains a self-sustaining speed. In tracing the flow of fuel through the control as schematically illustrated in 1r'iigure 2, it may be assumed that the engine is operating at idle speed at ground level, in which event the regulator valve 18 would be partly open under the influence of the idle spring 56 and the governor weights 50. Fuel ows to the entrance chamber 21 by way of conduit 20' at a P1 pressure determined by the setting of the by-pass valve 23, then across the regulator valve 18 to chambers 15, 15 (P2 pressure), and thence across the metering restriction 34 to metered fuel chamber 35 (P4 pressure), from which it flows by way of conduit 37, fuel manifold 11 and fuel line 12 to the burner nozzles 13. A limited quantity of fuel will also ow through the control jets 62 and thence through the density control circuit direct to the metered fuel chamber 35 in the manner heretofore described, this ow (compensating pressure P3) by-passing the throttle valve 3l.

The governor or throttle valve 31 is the prime control of fuel to the engine; it is positioned by the pilots throttle or control lever, who selects the desired engine speed. For every throttle lever position, there is a definite force set up by the governor spring 40 tending to open the governor or throttle valve 31, and for every engine speed, there is a denite thrust force set up by the governor weights 47 tending to close the said valve. When the pilot sets his throttle, the valve 31 will automatically seek a position of equilibrium, at which time the thrust force from the governor weights 47 equals the force of the spring 4t? and fuel is metered at a rate tending to maintain the engine speed constant.

Movement of the governor or'throttle valve 31 in a direction to increase the area of the metering restrictions 34 results in a decrease in the drop across said valve and a corresponding decrease in the differential across lthe regulator diaphragm 17, whereupon the regulator valve 18 moves towards open position, and fuel How increases to a point where the fuel head across the throttle valve is in balance with the regulator. Movement of the throttle valve 31 in a direction to restrict the ow of fuel results in an increase in throttle valve drop and a corresponding increase in the differential across the regulator diaphragm 17, whereupon the regulator valve 18 moves towards closed position and fuel ow decreases to a point where fuel head is again in balance with the regulator. Y

During acceleration and deceleration, the metering head or differential across the governor or throttle valve 31 and hence the rate of fuel feed will also increase and decrease with changes in entering air density in the manner heretofore described.

Referring to Figure 3, the curve chart plots fuel flow against engine speed, conditions being assumed to beat ground level density. The line 86 represents the fuel feed required for steady speed. At any point along this line, the governor or throttle valve 31 is assumed to be in equilibrium. The dot and dash line 87 represents the maximum delivery of the fuel pump 22. Let it be assumed that the engine is operating at point 88 and the pilot opens the governor or throttle valve 31 sufiiciently to accelerate to point 89'; then the fuel supplied during this period of acceleration will first follow the arrows from 88 to 9i), this initial increase in flow represented by the vertical arrows occurring as a result of the sudden increase in the effective area of the governor valve at the then existing speed. At point 9i), the rate of fuel feed has produced an operational temperature of say 1500" F. The regulator is now maintaining the fuel head across the throttle valve substantially proportional to the square of engine speed, and the rate of fuel feed follows the arrows on the maximum temperature line to point '91, where air flow departs from a linear relation to'engine speed, requiring an increase in the rate of fuel feed to maintain an operational temperature of l500 F. At point 91, however, the increase in engine speed has generated suiiicient pressure in governor chamber 79 to open valve 75, and fuel flows from the latter chamber across said valve to the density control circuit upstream of'variable orifice 61 and reduces the P2-P3 diterential, whereupon the regulator valve 18 opens and increases the Pz-P., differential or fuel head across the throttle valve and the rate of fuel feed increases to produce the required burner temperature for maximum eiiiciency. The engine now accelerates to point 89, where the allspeed governor weights 47 substantially balance the setting of the governor spring. Further increase in fuel flow then ceases and the governor valve closes slightly and reaches a condition of equilibrium at 89.

The slight departure of the fuel feed from the l500 F. line at theupper end of the acceleration curve is due to the fixed area of the oce 76; this could be cured by utilizing a properly contoured needle to control this orifice.

Should the pilot suddenly throttle back to the idle range, the fuel feed rate will follow the arrows from point 89 to point 92. The vertical arrows from point 89' to point 93 represent the initial reduction in fuel ow when the throttle valve is closed. However, since the engine is Still running at a relatively high rate of speed, the head or P2P4 differential will hold valve 75 open. This differential starts to diminish with engine speed at point 93 justV above the die-out region, and the valve 75 closes at point 94, whereupon the engine is operating only on idling fuel.

Although only one embodiment of the invention has been illustrated and described, certain changes in formv and relative arrangement of parts may be made as dictated by requirements and practical use.

We claim:

l. In a fuel feed system for a gas turbine engine having a burner, a fuel `conduit having a restriction therein, governor means for controlling the rate of fuel flow through said restriction including a centrifugal element adapted to rotate in relation to engine speed, means defining a gov- Y adapted ito discharge into said Ysupplied under pressure,

ernor feb-'amber Vcontaininga fluid nthepre'ssure Vof *Whichis Y augmented -thronghfrotation of said element, a yffueljpasparallel "wi-th said restriction, a Vfuel enrichment sage valve Vcontrolling ovv `of fuelfthrough said passage and Vadaptedto respond to the `pressure in said governor cham- Y ber Aand-produce an increase in the rate -of fuel feed to the burner, and another valve in said passage functionahleto control the head across said restriction as a function of entering air pressure and/ or temperature. V

V2. in a fuelfeed'and power control systemfor a gas turbine engine, a fuel conduit having a restriction therein, governor VrmeansY for controlling `the 'rate of` fuel ow through said `restriction including at least one centrifugal element adapted-'to rotate in relation to engine-speed,

means defining( a governor chamber Vcontaining fuel inV which said element rotates andaugments the normal fuell pressure, a fuelrpassage in parallel with said restriction, and a fuel enrichment'valve in said Apassage for producing ,Y anincr'ease in the ysupply of liquid fuel flowing through said restriction, said enrichment valve having an operative pressure connection with said governor chamber.

V3. In a fuel feed system for a gas turbine engine, Va fuel` Vconduit having alrestriction therein, governor means for Y ow'of fuel through said circuit, a fuel enrichment passage connectedxto said governor chamber and to Vsaid control circuit, and a fuel enrichment valve located in said latter passage -and adapted to respond to theV pressure generated in said governor chamber *and produce an increase in the rate. of fuel feed owing throughV said restriction.

4.V A fuel feedsysteni as claimed in claim 4 wherein said fuel enrichment passage communicates withV said'con-V trolcircuit at a point upstream'of said altitude responsive member. Y

5. In a fuelfeed system for a gas turbine erigine'having aburncr Vor generator to which air and liquid fuel are supplied under pressure, a fuel conduit having a feed VrestrictionV therein, a -throttle valve for varying the area rof said restriction to control the rate offuel feed to the burner, a governor operatively connected to said valve, meansdeining agovernor chamber noimally'rcontaining fuel when the system is in operation, a plurality of Ycen- ',trifugal governor elements located in said Ychamber and adapted toY rotate in relation to engine speed, a regulator valve'fo-r controlling the fuel head across the throttle valve asa function of engine speed, certain of said elements Y having `anioperative connectionvvith said throttle -valve Y and Yother of said elements with said regulator val-fe,'ro Vtation of said elemcnts, a rgmenting the normal fuel pres-Y sure in .said chamber, a density control circuit inparallelV Vwith said` throttle valve, a fuel enrichment passage having its inlet .communicating with said governor chamber and density .control circuit, and afuel enrichment valve controlling flow .of Vfuel through said enrichmentpassage, latter valve being responsive t6 the pressure generated by saidcentrifugal elements and f functioning to vary the fuel metering `head across the throttle valve.Y

6. Ina fuel feed:V systemfora gas turbine engine having afb'urner or generator to ywhichair and liquid fuel are a fuel control device comprising a fuel control section and a regulator section, valve located in saidcontro'l section, a regulator valve Vfor controlling the fuel metering head across said throttle Vvalve located in said regulator section, governor means a throttle Y operatively 'connected te said fthrottle Y valveinc'lu'c'liiigY t least one centrifugal weight, lmeans dennin'g a chamber "ifn 'Y whichsaLd'vVeghtrOtateS, a control circuit including jafuel Y Y passagefinthe nature of'a bleed off ythe main` ilovvr across Y Y f the Vthrottle valve and in V'parallel `vvith the'latterian fa tude responsive valve in said control circuit, afue'l'enric ment circuit including a fuel passage originating in'saidV Y governor chamber andi-discharging' into'said control cir-,-V

cuit upstream of said altitude responsive valve, and afuel enrichment valve located in said latter passageV and adapted to respond to the pressure generated inrsaid governor chamber and vary thefuel metering head Vacross f said throttle valve. v

7. In a fuel feed system for'an engine,.a throttle valve andan associated governor for automatically' maintaining i Y Y the throttle Vvalve in a position for constant cngine'spe'edV Y ing a hydraulic fluid such as liquid fuel therein, andjafful enrichmentl valve responsive to the hydraulic Vpressureigeun erated by said element in said chamber-for automatic ly. increasing Ythe rate of fuelfeedV as a functionY Vof 'engine speed. Y

Y 8. In V.a fuel feeding system foraY gas turbine engine,V

a fuel conduit having arrestriction therein, means in `said Y conduitforregulating the fuel pressure drop across 'said restriction, a passage connected inrseries flow relation"r with said vregulating meansfand in parallel ilow relation.. with said restriction, altitude compensating means iin saidpassage Vfor modifying 4the action of the regulating means, Y'

and a fuel enrichment valve in said Apassage for further VVmodifying the action of the regulating means.

9. In a fuel feed systemfor a gasV turbine engine'Q-atlel'y conduit having a restriction therein, means 'in said conduit for regulating the fuel pressuredrop across `said restric tion, .and means operatively connected to said're'gulating i meansfonmdifying the pressure drop across` said ite-'- striction during operation of the engine, said meansV Vi11-v Vcluding altitudev compensating means. in series flow relation with said regulating means and fuelfair ratio4 enrich- Y ing means operative during an acceleration ofthe engineY to cause an abrupt increase in the ow ofvfuel through said restriction. Y i Y 1 l 10. In a fuel feed system fora' gas'turbine enginehaving a burner, a fuel conduit having a feed restriction there,-

in, a throttle valve for varying the area'of said restric. Y

tionV to control the rate of Vfuel feed to the burner, `a governor operatively connected to said throttle valve for varying fuel ilow'a's an inverse function of engine speed and including an elementwhich is adapted to rotate. in relation to engine speed, chamber means related to said f Yelement'in such a manner that the rotation of said element produces an augmented pressure in said chamber, and .a

device responsive to said augmented pressure ,for produc-V ing an increase in the rate of fuel feed to the burner ata predetermined engine speed'during van acceleration of the engine. Y Y

References Cited in the tile of this patent UNITED STATES rirrENTsr.y Y

2,414,322 Mock Jan. 1'4, 192171 2,581,276 Y Mock Ian. A'1.,51952 Y Y 2,644,513 Mock July 7, 1953 12,664,152 Davies f i Dec; 29, 179,535 2,689,606 Mock Vseptdrzi,V '1954 FonEiGN PATENTS 934,814y France 121171.19, 194:8 

